In recent years, more compacted video tape recorders (VTRs) are made available. Especially, 8-mm VTRs are realized in a greatly reduced size with a diminished weight for use with 8-mm-wide magnetic tape.
With the development of compact and light-weight VTRs, VTRs have been introduced into use which comprise a camera unit and a VTR unit as an assembly. It is also possible to realize a portable image reproduction system which comprises a liquid-crystal television set and a VTR in the form of an assembly. Further reduced sizes are severely required of such VTRs.
Accordingly, VTRs are proposed which are variable for different modes in the depthwise length along the direction of insertion of the cassette as shown in FIGS. 41 and 42 (Unexamined Japanese Patent Publication SHO. 61-271648).
The proposed VTR comprises a head cylinder 11 having a rotary magnetic head and mounted on a main chassis 1, a reel chassis 2 provided on the main chassis 1 and slidable toward or away from the head cylinder 11, and a supply reel support 21 and a take-up reel support 22 which are mounted on the reel chassis 2. The reel chassis 2 is driven by a chassis drive mechanism (not shown) coupled to a loading motor on the main chassis 1.
The supply reel support 21 and the take-up reel support 22 are driven by a known reel support drive mechanism having a swing idler coupled to a capstan motor.
FIG. 41 shows the recorder in a standby mode, in which the reel chassis 2 is partially projected from the main chassis as indicated at A. In this state, a tape cassette 150 is loaded on the reel supports 21, 22 on the reel chassis 2.
FIG. 42 shows the recorder in a play mode, in which the reel chassis 2 has been slidingly moved toward the head cylinder 11, which is in turn partly positioned in an opening B of the cassette 150. In this state, the magnetic tape is wound around the head cylinder 11 for recording or reproducing signals.
Thus, the depthwise length of the VTR can be reduced from L.sub.1 to L.sub.2 as illustrated. This renders the recorder convenient to carry about.
The present applicant invented a VTR comprising a reel chassis 2 slidably provided on a main chassis 1 as in the above VTR, and a pinch roller pressing mechanism of a construction different from those of the prior art as will be described below (see FIGS. 5 to 7). The mechanism of this VTR is disclosed in a pending patent application filed in the Japanese Patent office and not laid open yet.
The VTR includes a swing idler 110 which is coupled to a loading motor 31 for driving a supply reel support 21 and a take-up reel support 22. With the rotation of a loading motor 31, the idler 110 swings toward one of the reel supports and is eventually operatively connected to the reel support to transmit rotation thereto.
In the steps shown in FIGS. 5 and 6, a tape loading mechanism 5 operates to withdraw the magnetic tape off the supply reel and the take-up reel within the cassette and wind the tape around the head cylinder 11.
The tape is paid off from both the reels to avoid damage to the tape due to the friction between the head cylinder and the tape.
With reference to FIG. 7, the magnetic tape 151 is thereafter pressed against a capstan 12 by the pinch roller 81 of the pinch roller pressing mechanism 8 to transport the tape.
When a tape loading mechanism 5 performs an unloading operation from the state of FIG. 6 to the state of FIG. 5 after recording or playback, the tape withdrawn from the cassette is wound on the take-up reel by the rotation of the take-up reel 22.
However, in the course of development of the VTR of the pending application, the following problem became apparent.
With recording-reproduction systems of greatly reduced size such as 8-mm VTR, the magnetic tape is wound around the head cylinder through an angle of 270 degrees which is greater than is the case with conventional VTRs (about 180 degrees), so that the friction between the magnetic tape in travel and the periphery of the head cylinder is great. Accordingly, if the tape to be passed around the cylinder during tape rewinding or reverse playback is defaced or bears oil or condensation water deposited thereon, the tape is likely to be braked and come to a stop on the periphery of the cylinder. Since the tape is continuously paid off from the capstan toward the head cylinder in this case, the tape will slacken between the capstan and the head cylinder.
In such an event, the capstan conventionally stops rotating, followed by ejection or power turning-off procedure only.
Consequently, if the VTR is inclined or subjected to an impact with a slack, remaining in the tape, the tape will be greatly displaced from the specified path of travel and become entangled with the guide post or the like when the cassette is to be removed from the recorder.
Furthermore, the following problem is encountered if the tape loading-unloading system of conventional VTRs is employed as it is for the VTR of the pending application.
If the cassette is removed from the VTR with the magnetic tape completely wound up on the take-up reel after the completion of recording or playback and is thereafter loaded into the VTR again, followed by tape loading, the tape will be withdrawn only from the take-up reel, with the result that the tape is likely to be damaged by the friction between the tape and the head cylinder.